US4982246A - Schottky photodiode with silicide layer - Google Patents
Schottky photodiode with silicide layer Download PDFInfo
- Publication number
- US4982246A US4982246A US07/369,405 US36940589A US4982246A US 4982246 A US4982246 A US 4982246A US 36940589 A US36940589 A US 36940589A US 4982246 A US4982246 A US 4982246A
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- United States
- Prior art keywords
- layer
- photodiode
- schottky
- semiconductor
- conductive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 229910021332 silicide Inorganic materials 0.000 title claims description 4
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 title claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 15
- 239000010703 silicon Substances 0.000 claims abstract description 15
- 239000000758 substrate Substances 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims description 19
- 238000002161 passivation Methods 0.000 claims description 18
- 239000004065 semiconductor Substances 0.000 claims description 14
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 8
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 8
- 239000004020 conductor Substances 0.000 claims description 7
- 238000001465 metallisation Methods 0.000 claims description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 239000011651 chromium Substances 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 239000011733 molybdenum Substances 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- 239000010936 titanium Substances 0.000 claims description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 2
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- 239000010937 tungsten Substances 0.000 claims description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims 1
- 229910001887 tin oxide Inorganic materials 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 15
- 229910021417 amorphous silicon Inorganic materials 0.000 abstract description 12
- 238000000151 deposition Methods 0.000 abstract description 6
- 238000000059 patterning Methods 0.000 abstract description 2
- 229920002120 photoresistant polymer Polymers 0.000 abstract description 2
- 230000000873 masking effect Effects 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 238000005530 etching Methods 0.000 description 4
- 238000003384 imaging method Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 238000003331 infrared imaging Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- -1 palladium Chemical compound 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
- H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type
Definitions
- the present invention relates to photodiodes and, more particularly, to a novel method for fabricating Schottky photodiodes.
- Schottky photodiodes have received extensive use in imaging applications, particularly imaging for medical purposes such as infrared imaging, ultraviolet imaging, x-ray imaging and the like. Basically, light energy or similar electromagnetic energy, incident upon a photodiode, or an array of photodiodes, will create an electrical signal, or signals, which can be processed to produce an image which can be displayed by means of a cathode ray tube or the like.
- Conventional Schottky photodiodes are fabricated by depositing a base or bottom electrode on a principal substrate surface.
- a layer of doped amorphous silicon (a-Si) follows.
- a layer of intrinsic silicon (i-Si) is formed on the a-Si layer and a first layer of passivation material such as silicon nitride (SiN) or the like is formed over the i-Si layer.
- This multilayer "sandwich” is then patterned and etched with a first mask by known photolithographic techniques to form a diode island.
- a second layer of passivation material such as SiN is deposited over the diode island; both passivation layers are then patterned and etched with a second mask to form a via opening which exposes a portion of the i-Si layer top surface.
- a top electrode, or Schottky contact is disposed on the second passivation layer and on the exposed i-Si layer portion through the via opening. That area where the Schottky material electrically contacts the exposed i-Si portion is referred to as the active area. Problems can arise with this fabrication method because of pattern transfer errors between the photoresist mask and the second passivation layer in the second masking operation, which can cause the via opening to be misaligned with the diode island.
- the via opening formed in the second mask operation is made smaller than the top surface of the diode island; however, this reduces the size of the active area of the photodiode and adversely affects some photodiode performance characteristics, such as reduced signal-to-noise operation.
- a method for use in fabricating Schottky photodiodes includes the steps of: depositing a first metal layer on a principal substrate surface to form a bottom, or base, contact; forming a layer of doped amorphous silicon disposed on the first metal layer; forming a layer of intrinsic silicon on the doped amorphous silicon layer; depositing a second metal layer over the intrinsic silicon layer to form a Schottky contact in electrical contact with substantially all of the intrinsic silicon layer; and selectively patterning the Schottky contact and the silicon layers with the same mask to form a diode island.
- a layer of passivation material is deposited over the diode island to provide electrical isolation from adjacent Schottky photodiodes or the like and is patterned to form a via opening exposing a portion of the Schottky contact.
- a layer of transparent conductive material is then deposited on the passivation layer and through the via opening in electrical contact with the Schottky contact to electrically interconnect the Schottky photodiode to other photodiodes or the like.
- FIGS. 1A-1E are cross-sectional, side elevation views of the steps employed in a conventional Schottky photodiode fabrication method.
- FIGS. 2A-2E are cross-sectional, side elevation views of the steps employed in the Schottky photodiode fabrication method in accordance with the present invention.
- a first layer 10 of metallization is deposited on a principal surface 12 of a substrate 14 to form a bottom or base electrode.
- a layer 16 of amorphous silicon (a-Si) is deposited by chemical vapor deposition (CVD) or by plasma enhanced chemical vapor deposition (PECVD) and is doped to preferably have N+conductivity.
- a layer 18 of intrinsic silicon (i-Si) is deposited on N+ layer 16 and a first layer 20 of passivation material, usually silicon nitride (SiN), is deposited over i-Si layer 18.
- the silicon sandwich formed by layers 16, 18 and 20 is patterned and etched, in a first masking step, using known photolithographic techniques, to form a diode island 22 (FIG. 1B).
- a second layer 24 of passivation material, usually SiN, is formed over the diode island 22 as shown in FIG. 1C.
- a second masking operation is performed and the second and first passivation layers 20 and 24 are patterned and etched to form an aperture 26 therein (FIG. 1D) through which a portion 28 of the top surface 30 of i-Si layer 18 is exposed.
- another layer 32 of metallization is deposited, as by sputtering or evaporation, on passivation layer 24 and on exposed i-Si portion 28 through aperture 26, to form a Schottky contact to i-Si layer 18.
- Aperture 26 is made smaller than top surface 30 of i-Si layer 18 to minimize masking misalignment errors and etching errors when aperture 26 is formed to expose i-Si portion 28 on diode island 22, but the small aperture has the disadvantage of reducing the active area, defined by dimension "X" in FIG. 1E, which is the area where Schottky contact 32 makes electrical contact with i-Si layer 18.
- a layer 10' of conductive material is deposited on substrate surface 12'.
- Layer 10' may be any metal, such as chromium, titanium, tungsten, aluminum or alloys thereof, but is preferably molybdenum deposited by sputtering or evaporation to a thickness of about 4000 angstroms.
- a layer 16' of amorphous silicon (a-Si) is deposited to a thickness of . about 500 angstroms on conductive layer 10' by CVD or PECVD and layer 16' is doped to preferably have N+ type conductivity.
- a layer 18' of intrinsic silicon (i-Si) is deposited by CVD or PECVD to a thickness of between about 5,000 and 20,000 angstroms on N+ layer 16' and a Schottky contact layer 32' is deposited on i-Si layer 18'.
- Schottky contact layer 32' may be any metal which can form a silicide, such as palladium, and may be deposited to a thickness between 50 and 100 angstroms.
- Schottky contact layer 32', i-Si layer 18' and N+ layer 16' are patterned and etched by known photolithographic techniques to form diode island 22' (FIG. 2B).
- the active area defined by dimension "Y" in FIG. 2B is that area where Schottky contact 32' is in electrical contact with i-Si layer top surface 30'.
- the unreduced active area results because Schottky contact layer 32' is deposited before diode island 22' is formed; therefore, only a single masking step is required to form the photodiode and misalignment and etching problems between the Schottky contact 32' and diode island 22' are eliminated.
- a layer 34 of a light transmissive passivation material such as SiN and the like, is deposited over diode island 22' to provide electrical isolation from adjacent photodiodes or other circuit components (not shown).
- Passivation layer 34 may be deposited to a thickness of about 2000 angstroms or to a thickness sufficient to ensure adequate step coverage over the photodiode island.
- Passivation layer 34 is then patterned and etched by standard photolithography to form a contact opening 36 which exposes a portion 32'a of Schottky contact 32' (FIG. 2D).
- a light transmissive conductive layer 38 such as indium tin oxide (ITO), is deposited on passivation layer 34 and on Schottky contact portion 32'a through contact opening 36; conductive layer 38 is for making electrical connections between Schottky photodiode 22' and other photodiodes or devices (not shown).
- Conductive layer 38 preferably has a thickness of about 600 angstroms but should be thick enough to provide adequate step coverage.
- Contact opening 36 and exposed contact portion 32'a may be small relative to the entire top surface of Schottky contact 32' to avoid misalignment between conductive layer 38 and photodiode island 22'. While conductive layer 38 may electrically contact Schottky contact 32' in a relatively small area indicated by dimension "Z" in FIG.
- the large area of contact between Schottky contact 32' and i-Si layer top surface 30' (active area Y) is effective to overcome the disadvantages of the prior art method illustrated in FIGS. 1A-1E.
- active area Y the large area of contact between Schottky contact 32' and i-Si layer top surface 30'
- a plurality of Schottky photodiodes are formed in an array on the substrate; the totality of different signals, created by electromagnetic energy incident upon all of the photodiodes, are processed to generate an image.
- the signals may be processed to create an image displayable on a cathode ray tube (CRT) or the like, or the information may be transferred to a mass storage device (such as a magnetic tape and the like) for later analysis.
- CTR cathode ray tube
Abstract
Description
Claims (8)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/369,405 US4982246A (en) | 1989-06-21 | 1989-06-21 | Schottky photodiode with silicide layer |
US07/586,920 US5010018A (en) | 1989-06-21 | 1990-09-24 | Method for forming Schottky photodiodes |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/369,405 US4982246A (en) | 1989-06-21 | 1989-06-21 | Schottky photodiode with silicide layer |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US07/586,920 Division US5010018A (en) | 1989-06-21 | 1990-09-24 | Method for forming Schottky photodiodes |
Publications (1)
Publication Number | Publication Date |
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US4982246A true US4982246A (en) | 1991-01-01 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US07/369,405 Expired - Fee Related US4982246A (en) | 1989-06-21 | 1989-06-21 | Schottky photodiode with silicide layer |
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US (1) | US4982246A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5278444A (en) * | 1992-02-26 | 1994-01-11 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Planar varactor frequency multiplier devices with blocking barrier |
US5449924A (en) * | 1993-01-28 | 1995-09-12 | Goldstar Electron Co., Ltd. | Photodiode having a Schottky barrier formed on the lower metallic electrode |
US6462393B2 (en) | 2001-03-20 | 2002-10-08 | Fabtech, Inc. | Schottky device |
JP2012023362A (en) * | 2010-06-18 | 2012-02-02 | Semiconductor Energy Lab Co Ltd | Photoelectric conversion element, manufacturing method of photoelectric conversion element, display device, and electronic apparatus |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4163677A (en) * | 1978-04-28 | 1979-08-07 | Rca Corporation | Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier |
JPS604274A (en) * | 1983-06-22 | 1985-01-10 | Toshiba Corp | Photoelectric conversion member |
US4532373A (en) * | 1983-03-23 | 1985-07-30 | Agency Of Industrial Science & Technology, Ministry Of International Trade And Industry | Amorphous photovoltaic solar cell |
US4543442A (en) * | 1983-06-24 | 1985-09-24 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | GaAs Schottky barrier photo-responsive device and method of fabrication |
-
1989
- 1989-06-21 US US07/369,405 patent/US4982246A/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4163677A (en) * | 1978-04-28 | 1979-08-07 | Rca Corporation | Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier |
US4532373A (en) * | 1983-03-23 | 1985-07-30 | Agency Of Industrial Science & Technology, Ministry Of International Trade And Industry | Amorphous photovoltaic solar cell |
JPS604274A (en) * | 1983-06-22 | 1985-01-10 | Toshiba Corp | Photoelectric conversion member |
US4543442A (en) * | 1983-06-24 | 1985-09-24 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | GaAs Schottky barrier photo-responsive device and method of fabrication |
Non-Patent Citations (6)
Title |
---|
Li, "A Proposed Novel MPN GaAs Schottky Barrier Solar Cell", Japanese Journal of Applied Physics, vol. 17 (1978), Supplement 17-1, pp. 291-294. |
Li, A Proposed Novel MPN GaAs Schottky Barrier Solar Cell , Japanese Journal of Applied Physics, vol. 17 (1978), Supplement 17 1, pp. 291 294. * |
Murarka, "Refractory Silicides for Integrated Circuits", J. Vac. Sci. Technol., 17(4), Jul./Aug. 1980, pp. 775-791. |
Murarka, Refractory Silicides for Integrated Circuits , J. Vac. Sci. Technol., 17(4), Jul./Aug. 1980, pp. 775 791. * |
Wu et al., "Nb/GaAs and NbN/GaAs Schottky Barriers", Appl. Phys. Lett., 50(5), Feb. 2, 1987, pp. 287-289. |
Wu et al., Nb/GaAs and NbN/GaAs Schottky Barriers , Appl. Phys. Lett., 50(5), Feb. 2, 1987, pp. 287 289. * |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5278444A (en) * | 1992-02-26 | 1994-01-11 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Planar varactor frequency multiplier devices with blocking barrier |
US5449924A (en) * | 1993-01-28 | 1995-09-12 | Goldstar Electron Co., Ltd. | Photodiode having a Schottky barrier formed on the lower metallic electrode |
US6462393B2 (en) | 2001-03-20 | 2002-10-08 | Fabtech, Inc. | Schottky device |
US6710419B2 (en) | 2001-03-20 | 2004-03-23 | Fabtech, Inc. | Method of manufacturing a schottky device |
JP2012023362A (en) * | 2010-06-18 | 2012-02-02 | Semiconductor Energy Lab Co Ltd | Photoelectric conversion element, manufacturing method of photoelectric conversion element, display device, and electronic apparatus |
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Owner name: GENERAL ELECTRIC COMPANY,, NEW YORK Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:POLASKO, KENNETH J.;WEMPLE, IVAN L.;REEL/FRAME:005095/0465 Effective date: 19890614 |
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